Transcript

The giraffe’s looong evolution. I’m Bob Hirshon and this is Science Update.

Giraffes have seven cervical vertebrae in their necks just like most other mammals. So how did they get to be the tallest creatures on earth? To find out, scientists sequenced the giraffe’s genome and that of the okapi, a close relative of much more modest stature.

DOUGLAS R. CAVENER (Penn State):

We identified essentially 70 genes that show what we call ‘multiple signs of adaptation’ in the giraffe, as compared to okapi and other mammals.

HIRSHON:

That’s Penn State experimental geneticist Douglas Cavener. He and his colleagues write in Nature Communications that the giraffe’s neck vertebrae lengthened over a 15 to 20 million year period, evolving in tandem with genes that regulate the cardiovascular system.

CAVENER:

It has to have a very high blood pressure and a turbo-charged heart to get the blood up to the brain.